Low-k dielectric CVD precursors and uses thereof

ABSTRACT

Methods for depositing a low-k dielectric film on the surfaces of semiconductors and integrated circuits are disclosed. A Si—O—C-in-ring cyclic siloxane precursor compound is applied to the surface by chemical vapor deposition where it will react with the surface and form a film having a dielectric constant, k, less than 2.5. The compound generally has the formula (—O—R 1 —O—)SiR 2 R 3  or the formula (—R 1 —O—)SiR 2 R 3 .

[0001] This application claims priority from Provisional PatentApplication Serial No. 60/239,332 filed Oct. 10, 2000.

FIELD OF THE INVENTION

[0002] The present invention provides for methods for forming a low-kdielectric thin film on semiconductors or integrated circuits using aSi—O—C-in-ring cyclic siloxane compound as a low-k dielectric CVDprecursor.

BACKGROUND OF THE INVENTION

[0003] The increase in semiconductor design integration by feature sizereduction has resulted in increased levels of interconnect and increasedutilization of dielectric low-k thin films. The dielectric film is usedas insulation around metal lines of a device and contributes to the RCtime constant that controls the device speed. As the semiconductorindustry has striven to reduce resistance (R) by the use of coppermetallization, the push to the use of low-k dielectrics is to reducecapacitance (C). Reducing capacitance by lowering the dielectricconstant k to the inter and intra level dielectric (ILD) film canimprove device performance by reducing the RC time delay, decreasing thecross talk between adjacent metal lines and lowering the powerdissipation.

[0004] Traditionally, the material of choice for the ILD is silicondioxide (SiO₂) which can be prepared using silane, disilane or siloxaneprecursors in an oxidizing environment. The most popular depositiontechniques for depositing ILD are chemical vapor deposition (CVD), lowtemperature plasma-enhanced CVD (PECVD), or high density plasma CVD(HDPCVD). However, the dielectric constant of the deposited SiO₂ isrelatively high at 4.0.

[0005] As the semiconductor industry moves to thinner metal lines, ILDmaterials must have smaller dielectric constants. Industry publicationshave indicated that low-k materials with k values from 2.7 to 3.5 wouldbe needed for 150 and 130 nm technology nodes. When the industry movesto 100 nm technology node and below that in the future, extra low-k(ELK) materials having a k value from 2.2 to 2.6 and ultra low-k (ULK)materials with a k value less than 2.2 will be necessary.

[0006] The semiconductor industry has developed several low-k materialsto replace silicon dioxide that are inorganic, organic or hybridmaterials. These materials can be deposited by either chemical vapordeposition (CVD) or spin-on deposition (SOD) methods. The CVD techniqueutilizes traditional vacuum tools for depositing low-k films thatinclude lower temperature plasma enhanced CVD (PECVD) and high densityplasma CVD (HDPCVD). The SOD method uses spin coaters that have shownbetter extendibility to ELK or ULK by introducing pores in nanometersizes. Low-k materials such as fluorinated silicate glass (FSGk˜3.5-3.8), carbon or carbon fluorine based films and carbon-doped SiO₂utilize CVD techniques. Other low-k materials, such as polyimide(k˜2.9-3.5), hydrogen silsesquioxane (HSQ, k˜2.7-3.0) and polyaryleneethers (k˜2.6-2.8), can be deposited using SOD techniques.

[0007] As such, a number of technologies to provide lower dielectricconstant CVD materials have been demonstrated in the 3.5 to 2.6 range.However, there are far fewer alternatives for k values at or below 2.5for CVD materials in ELK/ULK applications. The present inventionprovides for new materials for use as extra low dielectric CVDprecursors in extra low-k CVD materials for the semiconductor industry.

[0008] Given the desires of the semiconductor industry for lower k valuematerials, new low-k CVD materials are being sought. The presentinvention provides a novel class of compounds useful for forming a filmon a semiconductor or integrated circuit by acting as a precursor forthe film formed when the compound is applied.

SUMMARY OF THE INVENTION

[0009] The present invention provides for methods for fabricating adielectric thin film on semiconductors and integrated circuits using aSi—O—C-in-ring cyclic siloxane compound. The dielectric film formed willbe an organosilicon polymer film having low-k dielectric properties.

[0010] The Si—O—C-in-ring cyclic siloxane compounds are generally1,3-dioxa-2-silacyclohydrocarbons and 1-oxa-2-silacyclohydrocarbons. Oneor more than one carbon atom in the hydrocarbon chain of above cyclicsiloxane compounds can be substituted by one or more than one siliconatom.

[0011] The present invention also provides for methods for depositing alow-k dielectric film on a semiconductor or integrated circuit using aSi—O—C-in-ring cyclic siloxane compound.

[0012] The Si—O—C-in-ring cyclic siloxane compounds are precursors tothe film formed. When these siloxane precursors are applied to thesurface of a semiconductor or integrated circuit, they will react on thewafer surface forming a dielectric film. The ring opening polymerizationof these cyclic compounds will form a dielectric film or layer that willhave a k value between 2.0 and 2.5.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] The present invention provides for a method of fabricating adielectric film on a semiconductor or integrated circuit wherein thedielectric film will be low-k comprising applying to the surface of thesemiconductor or integrated circuit a Si—O—C-in-ring cyclic siloxanecompound precursor.

[0014] The Si—O—C-in-ring cyclic siloxane compound is selected from thegroups consisting of 1,3-dioxa-2-silacyclohydrocarbons and1-oxa-2-silacyclohydrocarbons. The 1,3-dioxa-2-silacyclohydrocarbonsgenerally have the formula (—O—R₁—O—)SiR₂R₃, wherein R₁ is saturated orunsaturated hydrocarbon with from 1 to 7 carbon atoms.R₂ and R₃ can bethe same or different, and they are H, or methyl, or vinyl, or otherhydrocarbons containing two or more than two carbon atoms. The1-oxa-2-silacyclohydrocarbons generally have the formula (—R₁—O—)SiR₂R₃,where R₁ is saturated or unsaturated hydrocarbon with from 1 to 7 carbonatoms .R₂ and R₃ can be the same or different, and they are H, ormethyl, or vinyl, or other hydrocarbons containing two or more than twocarbon atoms.

[0015] One or more than one carbon atom in R₁ of above cyclic siloxanecompounds can be substituted by one or more than one silicon atom.

[0016] Specific examples of these compounds include but are not limitedto 2, 2-dimethyl-1,3-dioxa-2-silacyclopentane, 2,2-dimethyl-1,3-dioxa-2-silacyclohexane, or2,2,4,4,6-pentamethyl-1,3-dioxa-2-silacyclohexane,

[0017] and 2-vinyl-2-methyl-1,3-dioxa-2-silacyclopentane,2-vinyl-2-methyl-1,3-dioxa-2-silacyclohexane, or2-vinyl-2,4,4,6-tetramethyl- 1,3-dioxa-2-silacyclohexane,

[0018] and 2,2-dimethyl-1-oxa-2-silacyclohexane, or its derivatives,

[0019] The films that are formed using the above-describedSi—O—C-in-ring cyclic siloxane compounds will have dielectric constants,k, of below 2.5 in the range of about 2.0 to about 2.5.

[0020] The Si—O—C-in-ring cyclic siloxane compounds of the presentinvention can be prepared by conventional methods. For example, Lin etal. (Syn. Comm. 1997, 27(14), 2527-2532) demonstrates a synthesis methodfor 2,2-dimethyl-1,3-dioxa-1-silacycloalkane compounds. Schubert et al.(Chem. Ber. 1995, 128, 1267-1269) demonstrates a conversion ofhydrosilanes to alkoxysilanes using an efficient catalyst system.Nedogrei et al. (Zh. Prikl Khim, 1988, 61(4), 937-940) demonstrates thattransacetalization of a 1,3-dioxa-2-silacyclo compound with substituteddiols in dioxane containing acid catalysts gave 16-75% of thecorresponding dioxasilacycloalkanes. A modified synthesis method wasalso developed in this invention for preparing1,3-dioxa-2-silacyclohydrocarbons. In this method, 1.0 equivalent ofdimethyldimethoxysilane was mixed with 1.2 equivalents of a diol. To it,an acidic catalyst, TFA, was added. The optimal TFA concentration is4×10⁻⁵ M. The mixture was refluxed for 24 hours. After that, thestoichiometric amount of calcium hydride was added to neutralize theacid. The product was isolated by fractional distillation at atmosphericpressure. The yield was about 65-70%.

[0021] The low-k dielectric films formed by the compounds of the presentinvention are deposited using pyrolytic or plasma-assisted CVDprocesses. The siloxane precursor will react or polymerize on thesurface of the wafer forming the dielectric layer. The reaction, inpart, results in the opening of the cyclic structure and gives bettercontrol of organic content and the steric effect of the organic groupsin the finished film. Reduction of film density and introduction of nanosize pores help to achieve lower k values.

[0022] The present invention provides for low-k precursor chemistriesand process methods of depositing low-k film using CVD techniques. Theprocess system comprises a precursor delivery manifold system, a vacuumchamber as a plasma CVD reactor, a wafer substrate, and a computercontrol system.

[0023] The low-k precursor of this invention is injected into vacuumchamber with or without a carrier gas. Depending upon the physicalproperties of a member of the low-k precursor family, either liquid orvapor phase precursor is delivered by a manifold system to the vacuumchamber. The low-k precursor material is placed in a metallic sourcebubbler. Both pressure and temperature of the bubbler are controlled.For high vapor pressure precursors (>5 Torr at source temperature from25° C. to 100° C.), a direct vapor delivery method based on a pressuremass flow controller can be employed. Typically, the downstream deliveryline and a shower head in the vacuum chamber are heat traced to avoidany condensation. The precursor can be also delivered using a liquidinjection method at room temperature. The liquid phase precursor orsolution of solid phase precursor can be injected to a vaporizer whereit is located at the vacuum chamber. The vaporizer converts liquid phaseprecursor into vapor phase precursor at the point-of-use. In eithercase, the precursor is delivered at a rate from 1 sccm to 1000 sccm bythe manifold system. Most precursors in this invention are in a liquidstate at room temperature. The vapor pressure curves in a temperaturerange from −10° C. to 150° C. were obtained using an absolute techniquethat we have developed. Typically, the pure vapor of a precursor isdelivered using an MKS pressure based mass flow controller at 60° C.

[0024] The low-k precursor family of this invention contains thenecessary components for making low-k dielectric layers. Thesecomponents are atoms of silicon, oxygen, carbon, and hydrogen.Therefore, the low-k precursors can be directly used in making the low-kfilms of the present invention. An additional oxygen containingprecursor, such as O₂ or N₂O, is optional. The additional oxidant andoptional inert carrier gases are delivered using thermal mass flowcontrollers.

[0025] The vacuum chamber is a chemical vapor deposition (CVD) reactor.One viable CVD reactor in which the methods of this invention arepracticed is a parallel plate single wafer reactor. The process can beeither pyrolytic or plasma-assisted CVD. The total pressure in thereactor is controlled from 0.01 mTorr to 100 Torr. RF power is appliedto the upper electrode or the shower head. The RF power excites theprecursor vapors that have been inputted into the vacuum chamber andgenerates reactive plasma. The frequency of RF is typically in the rangeof 1 kHz to 3 GHz. A frequency of 13.56 MHz is typical .The RF power canbe varied from 1 to 1000 W. The preferred RF power is from 50 to 300 W.The RF power can be pulsed by alternating between on and off. When theduration of RF power on equals zero, the pyrolytic CVD condition isobtained.

[0026] A semiconductor substrate, typically a silicon wafer, is placedonto the bottom electrode. The size of the substrate can be up to 300 mmin diameter. The bottom electrode is heated by either electricalresistance heaters or by radiation heaters. The wafer temperature iscontrolled up to 600° C. The distance from the bottom electrode to theupper electrode can be also varied. Precursors deposited on the hotwafer surface will react and polymerize and this reaction andpolymerization is driven by reactive species, thermal and ring strainenergies. In this process, the opening and retention of the precursorring structures of the present invention can be controlled within thelow-k films.

[0027] A computer system controls the precursor delivery, RF powers,vacuum and pressure in the CVD chamber, as well as the temperature inthe delivery manifold and in the reactor.

[0028] A low-k film with a thickness up to 10 microns can then becharacterized for its thermal, mechanical, and electrical properties. Ak value is obtained using aluminum dots MIS capacitance (C-V)measurements at 1 MHz.

EXAMPLES

[0029] General synthesis method for 1,3-dioxa-2-silacyclohydrocarbons:

[0030] 1.0 Equivalent of dimethyldimethoxysilane was mixed with 1.2equivalents of a diol. To it, an acidic catalyst, TFA, was added. Theoptimal TFA concentration is 4×10⁻⁵ M. The mixture was heated at refluxfor 24 hours. After that, the stoichiometric amount of calcium hydridewas added to neutralize the acid. The product was isolated by fractionaldistillation at atmospheric pressure. The yields and thecharacterization data were listed below for selected compounds.

[0031] 2,2-dimethyl-1,3-dioxa-2-sila-cyclopentane (compound 1)

[0032] Yield: 60%. APCI MS (m/z): 149.2 (100%, C₄H₁₀SiO₂·CH₃OH); ¹H NMR(200 MHz, CDCl₃, ppm): d=−0.1 (2 CH₃), d=3.2 (2 CH₂); ¹³C NMR (50 MHz,CDCl₃, ppm): d=−5.8 (2 CH₃), d=49.1 (2 CH₂).

[0033] 2,2-dimethyl-1,3-dioxa-2-sila-cyclohexane (compound 2)

[0034] Yield: 65%. ¹H NMR (200 MHz, Benzene-d6, ppm): d=0.1 (s, 6H,2CH₃), 1.4 (m, 2H, CH₂), 3.8 (m, 4H, 2CH₂). ¹³C NMR (50 MHz, Benzene-d6,ppm): d=−1 (Si—C), 32 (CH₂), 64 (OCH₂). Elemental analysis: calculated(%): C, 45.4, H, 9.2; found: C, 45.4, H, 9.1. APCI MS (with CH₃OH as amobile phase): calcd.: 132.1; found: 133.0 [M+H⁺, 100%], 221.0[M+CH₃O+(CH₃)₂Si^(·), 58%], 165.0 [M+CH₃OH+H⁺, 43%], 252.7[M+Si(CH₃)₂+2CH₃O+H⁺, 24%], 265.0 [M+M+H⁺, 13%]. FT-IR (cm ⁻¹): 1255.0(m); 1143.8 (s); 1090.2 (vs); 973.7 (w); 930.9 (s); 846.2 (vs); 793.4(vs); 745.6 (w); 711.7 (w).

[0035] 2,2,4-trimethyl-1,3-dioxa-2-sila-cyclohexane (compound 3)

[0036] Yield: 67%. ¹H NMR (200 MHz, Benzene-d6, ppm): d=0.1 (s. 6H,2CH₃), 1.2 (m, 2H, CH₂), 1.4-1.7 (m, 4H, CH+CH₃), 3.9-4.1 (m, 2H, CH₂).¹³C NMR (50 MHz, Benzene-d6, ppm): d=−0.5 (Si-CH₃), 25 (C—CH₃), 39(CH₂), 63 (OCH), 70 (OCH₂). Elemental analysis: calcd. (%): C, 49.3, H,9.6; found: C, 49.3, H, 9.7. APCI MS (CH₃OH as a mobile phase):calculated: 146.1; found: 147.0 [M+H⁺, 100%], 178.9 [M+CH₃OH+H⁺, 50%],221.0 [M+O—Si(CH₃)_(2,) 67%], 293.1 [M+M+H⁺, 46%]. FT-IR (cm⁻¹): 1378.6(w); 1254.8 (m); 1157.6 (m); 1103.0 (s); 982.1 (m); 964.8 (s); 887.0(s); 847.3 (s); 793.7 (s); 743.0 (w); 716.4 (w).

[0037] 2,2,4,6-tetramethyl-1,3-dioxa-2-sila-cyclohexane (compound 4)

[0038] Yield: 63%. ¹H NMR (200 MHz, Benzene-d6, ppm): d=0.1 (m, 6H,2CH₃), 1.1-1.5 (m, 8H, 2CH₃+CH₂), 3.9-4.2 (m, 2H, 20CH). ¹³C NMR (50MHz, Benzene-d6, ppm): d=−0.2 (Si—CH₃), 24 (CH₃), 45 (CH₂), 68 (OCH).Elemental analysis: calcd. (%): C, 52.4, H, 10.1; found: C, 52.4, H,10.1. APCI MS (CH₃OH as a mobile phase): calculated: 160.1; found: 161.1[M+H⁺, 100%], 195.0 [M+CH₃OH+H⁺, 78%], 280.9 [M+diol+CH₃OH+H⁺, 60%],321.2 [M+M+H⁺, 10%]. FT-IR (cm⁻¹): 1377.1 (w); 1254.7 (m); 1167.9 (m);1152.8 (m); 1117.6 (s); 978.2 (vs); 911.6 (m); 886.9 (w); 871.6 (w);839.0 (s); 793.1 (vs).

[0039] 2,2,4,4,6-pentamethyl-1,3-dioxa-2-sila-cyclohexane (compound 5)

[0040] Yield: 66%. ¹H NMR (200 MHz, Benzene-d6, ppm): d=0.2 (s, 6H,2CH₃), 1.1-1.6 (m, 11H, 3CH₃+CH₂), 4.2 (m, 1H, CH). ¹³C NMR (50 MHz,Benzene-d6, ppm): d=0.1 (Si—CH₃), 0.2 (Si—CH₃), 25 (CH₃), 28 (CH₃), 34(CH₃), 50 (CH₂), 66 (OCH), 73 (OC). Elemental analysis: calcd. (%): C,55.1, H, 10.4; found: C, 55.7, H, 10.4. APCI MS (CH₃OH as mobile phase):calcd.: 174.1; found: 174.9 [M+H⁺, 9%], 192.9 [M+H₂O+H⁺, 32%], 266.9[M+Si(CH₃)₂O+H₂O+H⁺, 53%], 367.0 [M+M+H₂O+H⁺, 100%]. FT-IR (cm⁻¹):1366.3 (w); 1254.9 (m); 1200.0 (w); 1164.3 (m); 1129.9 (w); 1092.1 (w);1054.8 (m); 1002.4 (s); 979.5 (s); 955.4 (m); 908.4 (m); 873.9 (s);852.3 (m); 837.8 (m); 791.1 (vs); 653.6 (m).

[0041] 2,2,4,4,6,6-hexamethyl-1,3-dioxa-2-sila-cyclohexane (compound 6)

[0042] Yield: 82%. ¹H NMR (200 MHz, Benzene-d6, ppm): d=0.2 (s, 6H,2CH₃), 1.2 (s, 2H, 4CH₃ a), 1.3 (s, 10H, 4CH₃ e), 1.6 (s, 2H, CH₂). ¹³CNMR (50 MHz, Benzene-d6, ppm): Elemental analysis: calculated (%): C,57.4, H, 10.7; found: C, H, APCI MS (CH₃OH as mobile phase):calcd.:188.1; found: 190.0 [M+2H⁺, 5%], 223.0 [M+CH₃OH+H⁺, 40%], 265.0[M+(CH₃)₂Si+H₂O+H⁺, 100%], 369.0 [M+Si(CH₃)₂O+SiOCH₃+H₂O 68%]. FT-IR(cm⁻¹): 1451.9 (vw); 1365.8 (w); 1255.8, (m); 1197.9 (s); 1025.7 (vs);958.0 (m); 868.9 (s); 790.5 (vs); 690.0 (w); 659.3 (m).

[0043] 2-vinyl-2,4,4,6-tetramethyl-1,3-dioxa-2-sila-cyclohexane(compound 7)

[0044] Yield: 70%. ¹H NMR (200 MHz, Benzene-d6, ppm): δ=0.2 (s, 3H,CH₃), 1.4 (m, 11H, 3CH₃, CH₂), 4.2 (m, 1H, CH), 6.0 (3H, (3H, CH₃),. ¹³CNMR (50 MHz, Benzene-d6, ppm): δ=−0.1 (Si—CH₃), 25 (CH₃), 28 (CH₃), 33(CH₃), 50 (CH₂), 66 (OC), 73 (OCH), 134 (Si—C₂H₃), 137 (Si—C₂H₃).Elemental analysis: calculated (%): C, 58.0, H, 9.7; found: C, 57.8, H,10.1. APCI MS (CH₃OH as mobile phase): calcd.: 186.3; found: 187.3(M+H⁺, 100%), 219 (M+CH₃). FT-IR (cm⁻¹): 1366.9 (m); 1255.3, (m); 1200.8(m); 1163.2 (s); 1129.3 (m); 1091.6 (m); 1054.5 (s); 1001.1 (s); 979.6(vs); 954.9 (s); 908.3 (m); 817.9 (m); 836.3 (m); 789.8 (s); 759.6 (s);715.9 (w).

[0045] 2-vinyl-2-methyl-1,3-dioxa-2-sila-cyclohexane (compound 8)

[0046] Yield: 78%. ¹H NMR (200 MHz, Benzene-d6, ppm): δ=0.2 (s, 3H,CH₃), 1.3 (m, 1H, CH₂, a), 1.6 (m, 1H, CH₂, e), 3.9 (m, 4H, 2CH₂), 6.0(m, 3H, C₂H₃) ;. ¹³C NMR (50 MHz, Benzene-d6,ppm): δ=−2.0 (Si—CH₃), 32.5(CH₂), 64.9 (2OCH₂), 135.0 (C₂H₃). Elemental analysis: calculated (%):C, 49.96, H, 8.39; found: C, 49.87, H, 8.83. APCI MS (CH₃OH as mobilephase): calcd.:144.2; found: 145.2 (M+H⁺, 100%). FT-IR (cm⁻¹): 1257.3(m); 1142.7 (s); 1089.2 (vs); 972.3 (m); 929.6 (s); 857.2 (s); 811.5(s); 771.8 (s); 708.2 (m).

[0047] Low-k film with 2,2-dimethyl-1,3-dioxa-2-sila-cyclohexane(compound 2) without any oxidants.

[0048] Precursor source temperature 50° C., delivery temperature 60° C.,source flow rate 4 sccm, wafer temperature 30° C., argon purge flow rate56 sccm, RF power 100 W, chamber pressure 300 mTorr, film refractiveindex is between 1.43 and 1.45 by a prism coupler, film dielectricconstant of aluminum dot capacitors is 2.13 at 1 MHz.

[0049] Low-k film with 2,2-dimethyl-1,3-dioxa-2-sila-cyclohexane(compound 2) with oxygen.

[0050] Precursor source temperature 50° C., delivery temperature 60° C.,source flow rate 4 sccm, wafer temperature 30° C., oxygen flow rate 29sccm, argon purge flow rate 56 sccm, RF power 100 W, chamber pressure300 mTorr, film refractive index is between 1.43 and 1.45 by a prismcoupler, film dielectric constant of aluminum dot capacitors is 2.52 at1 MHz.

[0051] To deposit the low-k film, either pyrolytic or plasma enhancedCVD can be used. Film dielectric constants as low as 2.0 can be achievedusing a single precursor of this invention without an oxidant precursor.Because of high vapor pressures of the precursors in this invention, wedeliver vapor directly to the CVD reactor. The delivery flow rate isfrom 1 sccm to 50 sccm. The wafer temperature is below 200° C. The filmdielectric constant is between 2.0 to 2.5.

[0052] While this invention has been described with respect toparticular embodiments thereof, it is apparent that numerous other formsand modifications of this invention will be obvious to those skilled inthe art. The appended claims and this invention generally should beconstrued to cover all such obvious forms and modifications which arewithin the true spirit and scope of the present invention.

Having thus described the invention, what we claim is:
 1. A method forfabricating a dielectric film having low-k values on a semiconductor orintegrated circuit surface comprising applying to said surface aSi—O—C-in-ring cyclic siloxane precursor wherein said precursor reactswith and deposits on said surface said dielectric film.
 2. The method asclaimed in claim 1 wherein said Si—O—C-in-ring cyclic siloxane compoundis selected from the group consisting of1,3-dioxa-2-silacyclohydrocarbons and 1-oxa-2-silacyclohydrocarbons. 3.The method as claimed in claim 2 wherein said1,3-dioxa-2-silacyclohydrocarbons have the formula (—O—R,—O—)SiR₂R₃wherein R₁ is saturated or unsaturated hydrocarbon with from 1 to 7carbon atoms, R₂ and R₃ are the same or different, and are selected fromthe group consisting of H, methyl, vinyl, or other hydrocarbonscontaining two or more carbon atoms.
 4. The method as claimed in claim 3wherein said 1,3-dioxa-2-silacyclohydrocarbon is1,3-dioxa-2-sila-2,2-dimethyl-cyclopentane.
 5. The method as claimed inclaim 2 wherein said 1-oxa-2-silacyclohydrocarbons have the formula(—R₁—O—)SiR₂R₃, where R₁ is saturated or unsaturated hydrocarbon withfrom 1 to 7 carbon atoms, one or more than one carbon atom in R₁ can besubstituted by a silicon atom, R₂ and R₃ are the same or different, andare selected from the group consisting of H, methyl, vinyl, or otherhydrocarbons containing two or more carbon atoms.
 6. The method asclaimed in claim 5 wherein in said formula R₁ is saturated orunsaturated hydrocarbon with from 1 to 7 carbon atoms, and one or morethan one carbon atom in R₁ can be substituted by one or more than onesilicon atom.
 7. The method as claimed in claim 5 wherein said1-oxa-2-silacyclohydrocarbon is 2,2-dimethyl- 1-oxa-2-sila-oxacyclohexane.
 8. The method as claimed in claim 1 whereinsaid dielectric film has a k value below 2.5.
 9. The method as claimedin claim 8 wherein said dielectric film has a k value in the range ofabout 2.0 to about 2.5.
 10. The method as claimed in claim 1 whereinsaid Si—O—C-in-ring cyclic siloxane precursor is deposited on thesurface of the semiconductor or integrated circuit using chemical vapordeposition.
 11. The method as claimed in claim 10 wherein said chemicalvapor deposition is pyrolitic or plasma-assisted.
 12. The method asclaimed in claim 10 wherein said precursor is in either the vapor phaseor the liquid phase prior to deposition.
 13. The method as claimed inclaim 10 wherein said precursor is a single precursor, thereby notrequiring an additional oxidant compound.
 14. The method as claimed inclaim 1 further comprising applying said precursor with an additionaloxidant compound.
 15. The method as claimed in claim 1 wherein said theratio of opening and retention of the precursor ring structure on saidsurface can be adjusted during chemical vapor deposition.